The present invention relates to a device for discontinuous separation of solid particles from a liquid by centrifugal sedimentation thereof, comprising a vessel rotatable about a vertical axis, said vessel having an inlet for the liquid which is to be separated, a separation zone with sedimentation surface elements, upper and lower collection chambers communicating with the separation zone, an outlet for liquid which has been freed of particles in the separation zone, and an outlet which can be opened and closed, for particle sediment collected on the sedimentation surface elements. Centrifugal separators are used for among other things:
separation and extraction of yeast, starch, kaolin and the like PA1 separation of oil, grease and the like from a liquid mixture PA1 purification and clarification of high value liquids such as beer, wine, oils etc PA1 purification of waste flows. PA1 should be able to separate small solid particles with a density close to the continuous liquid phase at moderate speeds, i.e. g-numbers below 100 PA1 lower investment requirements than for current centrifuges with similar capacity PA1 lower energy requirements than for present machines with similar capacity PA1 must be reliable and not cause stoppages due to clogging for example, i.e. must have a high accessibility PA1 should be compact and simple to install PA1 the sediment should have high dry substance ratio PA1 should be able to withstand relatively aggressive liquids PA1 should be able to be pasteurized at temperatures slightly below 100.degree. C. PA1 should be able to be washed without dismantling.
One method of making separation more effective is to increase the area of the separation surface elements and reduce the liquid depth as much as possible, which can be done by various methods. The most common method is to provide the rotor rotating about a vertical axis with conical plates provided with so-called staples, i.e. spacer elements, which guarantee a predetermined relatively small spacing between the plates, thus shortening the sedimentation distance.
Such centrifugal separators are, however, expensive to manufacture, since strict safety standards are required to prevent breakdowns which can be violent due to the large amounts of energy stored in the high-speed rotors, which generate thousands of g's. Furthermore, they consume great amounts of energy during operation. A risk of turbulent flow and breaking apart of particles is present at the inlet when the liquid is to be accelerated. Also in the gaps between the surface multiplying separation plates there is a risk of turbulent flow, which decreases the quality of separation. Emptying of sediment at the high rotational speeds disturbs the separation, and emptying is often incomplete. The emptying of sediment also uses great amounts of energy and there is the risk of clogging. Finally, the sediment can be damaged during emptying.
A major purpose of the present invention is to suggest a centrifugal separation device which eliminates in any case most of the above mentioned deficiencies in known centrifugal separators and which can fulfill the following requirements of efficient separation of both process and waste flows:
Thus, a separator is sought which has the ordered laminar flow of the static separator and which, in combination with a reasonable g-number, provides a greater separation capacity at a more efficient smaller installation volume.